Phoenix Suns (2013–2018) 2013–14 season Len was selected fifth overall by the
Phoenix Suns in the 2013 NBA draft. Len was the second international-born player to be selected in that draft, behind the first overall selection in
Canadian-born
Anthony Bennett, as well as the highest-selected
Ukrainian-born player to be drafted in the NBA, which was a record previously held by
Vitalii Potapenko in 1996. He was also the first Suns player to be taken in the top 5 of an NBA draft since
Armen Gilliam in 1987. Due to his ankle surgeries, Len did not join the Suns for the
2013 NBA Summer League. On July 12, 2013, Len had surgery on his right ankle due to a
stress fracture. He signed with the Suns on August 29, 2013, and was cleared to practice with them by early September. Len made his NBA debut on November 1, 2013, at home in a close victory against the
Utah Jazz. He sat out seven games before returning on November 19 against the
Sacramento Kings. However, a day later, Len re-injured his left knee and missed over six weeks before returning on January 7 against the
Chicago Bulls. Len had his first 10-rebound game in a 126–117 win over the
Milwaukee Bucks on January 29, 2014.
2014–15 season In July 2014, Len joined the Phoenix Suns for the
2014 NBA Summer League. In the Suns' first game of the Summer League, Len recorded 6 points and 6 rebounds against the
Golden State Warriors before fracturing his right pinkie finger and was subsequently ruled out until training camp. On October 7, 2014, a day before the Suns' first pre-season game of
2014 against Brazilian club
Flamengo, Len fractured the same pinkie finger again, forcing him to the sidelines once more. He returned to action two weeks later in the Suns' pre-season game against the
Los Angeles Clippers on October 22. On October 31, 2014, Len recorded his first career double-double with career-highs in points and rebounds with 10 and 11, respectively, in the Suns' 94–89 win over the
San Antonio Spurs. On November 17, he scored a then career-high 19 points in a 118–114 win over the Boston Celtics. Len started his first game on December 15 against the
Milwaukee Bucks and continued to start for the Suns until February 5 when injured his ankle after a failed alley-oop attempt in the third quarter against the
Portland Trail Blazers. After missing three games due to the injury, he returned to action on February 20 to record 11 points, 10 rebounds and a career-high six blocks in a loss to the Minnesota Timberwolves. On April 2, he underwent successful surgery to repair his broken nose, an injury he suffered against the Portland Trail Blazers on March 30. He subsequently missed the final seven games of the season.
2015–16 season In July 2015, Len re-joined the Suns for the
2015 NBA Summer League in Las Vegas where in five games, he averaged 10.8 points and 9.8 rebounds per game. Following the conclusion of the Summer League, Len began training with his new teammate
Tyson Chandler, as well as rival center and one of Len's personal favorite players,
Tim Duncan, throughout the off-season. On December 9, Len recorded a then career-high 20 points and 14 rebounds in a 107–104 win over the
Orlando Magic. On January 11, he was ruled out for three games with a left hand sprain. On February 4, he recorded 12 points and a career-high 18 rebounds in a 111–105 loss to the
Houston Rockets. On February 21, he recorded a then career-high 23 points and 13 rebounds in a 118–111 loss to the
San Antonio Spurs. He went on to set a new career high on March 4, recording 31 points along with 15 rebounds in a 102–84 win over the
Orlando Magic. Two days later, Len recorded 19 points, 16 rebounds and a career-high 6 assists in a 109–100 win over the
Memphis Grizzlies. On March 17, he recorded his 10th straight game with 10+ rebounds. On April 7, he recorded a career-high seven assists in a 124–115 win over the Houston Rockets. Len appeared in 78 games for the Suns in 2015–16, starting in 46 of them, both career highs. He recorded 19 double-doubles and finished with averages of 9.0 points, 7.6 rebounds and 1.2 assists, all career highs. On November 8, he recorded 16 points and a season-high 14 rebounds in a 107–100 win over the
Detroit Pistons. On December 9, he recorded 14 points, 13 rebounds and a season-high five blocks off the bench in a 119–115 win over the
Los Angeles Lakers. On February 10, 2017, he was suspended one game without pay for leaving the bench area and entering the playing court during an altercation in the Suns' 110–91 loss to the
Memphis Grizzlies two days earlier.
2017–18 season Following the 2016–17 season, Len became a restricted free agent. On September 25, 2017, after spending the off-season looking to get a better deal, Len signed a one-year, $4.2 million qualifying offer to return to the Suns. On November 17, 2017, Len had 17 points and 18 rebounds in a 122–113 win over the
Los Angeles Lakers. On November 28, 2017, he tied a career high with 18 rebounds in a 104–99 win over the
Chicago Bulls. On December 16, 2017, he had 12 points and a career-high 19 rebounds in a 108–106 win over the
Minnesota Timberwolves. On March 2, 2018, he had six blocks in a 124–116 loss to the
Oklahoma City Thunder.
Atlanta Hawks (2018–2020) On August 3, 2018, Len signed a two-year, $8.5 million contract with the
Atlanta Hawks. On December 23, 2018, he had 15 points and a season-high 17 rebounds in a 98–95 win over the
Detroit Pistons. On March 3, 2019, he scored a then season-high 28 points with a career-high five 3-pointers in a 123–118 win over the
Chicago Bulls. On April 7, he scored a career-high 33 points, including a career-best six 3-pointers, in a 115–107 loss to the
Milwaukee Bucks.
Sacramento Kings (2020) On February 6, 2020, Len and
Jabari Parker were traded to the
Sacramento Kings in exchange for
Dewayne Dedmon and two second round picks.
Toronto Raptors (2020–2021) On November 29, 2020, Len signed with the
Toronto Raptors. He was waived by the Raptors on January 19, 2021, after 13 regular season games.
Washington Wizards (2021) On January 23, 2021, Len signed with the
Washington Wizards. In 57 appearances (40 starts) for Washington, he averaged 7.1 points, 4.4 rebounds, and 0.8 assists.
Second stint with Kings (2021–2025) On August 13, 2021, Len signed with the
Sacramento Kings. On January 7, 2022, Len recorded a season-high 18 points, alongside ten rebounds and two steals, in a 111–121 loss to the
Denver Nuggets. He made 39 appearances (10 starts) for Sacramento during the
2021–22 NBA season, averaging 6.0 points, 4.1 rebounds, and 1.2 assists. Len played in 26 games, including two starts, for the Kings during the
2022–23 NBA season, averaging 1.7 points, 2.3 rebounds, and 0.5 assists. He made 48 appearances for Sacramento in the
2023–24 NBA season, compiling averages of 2.5 points, 2.7 rebounds, and 1.0 assists. On July 8, 2024, Len re-signed with the Kings. He made 36 appearances (three starts) for Sacramento during the
2024–25 NBA season, averaging 1.4 points, 1.8 rebounds, and 0.8 assists.
Los Angeles Lakers (2025) On February 6, 2025, Len was traded back to the
Washington Wizards in a multi-team deal. On February 11, Len was waived by the Wizards and later signed with the
Los Angeles Lakers. He made 10 appearances (four starts) for Los Angeles, averaging 2.2 points, 3.1 rebounds, and 0.8 assists. On September 16, 2025, Len signed an Exhibit 9 contract with the
New York Knicks. He was waived by the Knicks prior to the start of the regular season on October 18.
Real Madrid On October 30, 2025, Len signed a multi-year contract with
Real Madrid of the
Liga ACB and the
EuroLeague. On November 7, Len made his team debut in a 101–92 win against
Barcelona in the
EuroLeague. ==National team career==